Power distributor and semiconductor device having the same

ABSTRACT

A power distributor includes a large reservoir capacitor, a switch coupled between at least one power supply line and the large reservoir capacitor, and a controller configured to turn on or off the switch based on whether a circuit block connected to the power supply line is in operation or not.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/429,483 filed on Apr. 24, 2009, now U.S. Pat. No. 8,102,159 issued onJan. 24, 2012, which claims priority of Korean patent application number10-2008-0134895 filed on Dec. 26, 2008. The disclosure of each of theforegoing applications is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

The present invention relates to a power distributor and a memory devicehaving the same. The power distributor in accordance with an embodimentof the present invention can be applied to other semiconductorintegrated circuits.

Lately, a typical semiconductor device including a dynamic random accessmemory (DRAM) has been required to operate with a low voltage and at ahigh speed. If a memory is driven with a low voltage at a high speed,the memory may have the following unintended consequences. That is, whenthe memory operates at a high speed, small inductance of a package or aboard may disturb supplying necessary power. If a memory is driven witha low supply voltage in order to reduce power consumption thereof, thenoise of a low power supply voltage may change circuit delay, and causethe memory to erroneously operate.

In order to overcome such consequences, a reduction in the noise of lowpower supply voltage is desired. That is, impendence between an externalpower supply and an on-chip circuit is desired to be controlled to besmall. For example, the impedance may be reduced by increasing thecapacitance of a reservoir capacitor at a peripheral circuit in a chip.Here, the reservoir capacitor may be used in a power distributor tominimize a voltage drop due to power consumption.

Although it is possible to obtain small impedance by using a reservoircapacitor having a small equivalent series resistance (ESR) with respectto radio frequency noise, a reservoir capacitor having very highcapacitance may be required for compensating low frequency noise.

Meanwhile, the capacitance of a reservoir capacitor is in proportion toa surface area of an electrode and in inverse proportion to a thicknessof a dielectric. Therefore, a thickness of a dielectric must be thin toobtain large capacitance in a given area. However, leakage current ofthe reservoir capacitor becomes a significant problem if the dielectricis thin.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention are directed to providinga power distributor for preventing leakage current of a large reservoircapacitor from increasing.

Exemplary embodiments of the present invention are directed to providingan integrated circuit having the power distributor.

Exemplary embodiments of the present invention are directed to providinga memory device having the power distributor.

In accordance with an exemplary aspect of the present invention, thereis provided a power distributor including a large reservoir capacitor, aswitching unit connected between at least one power supply line and thelarge reservoir capacitor, and a controller which turns on or off theswitching unit based on an operation state of a circuit block coupled tothe power supply line.

In accordance with another exemplary aspect of the present invention,there is provided an integrated circuit including a large reservoircapacitor, a circuit block configured to be driven with a power supplyvoltage from at least one power supply line, and a switching unitconfigured to receive information about whether the circuit block isenabled or disabled and to control an electrical connection between thelarge reservoir capacitor and the power supply line in response to thereceived information.

The integrated circuit may further include a sensor configured todetermine whether the circuit block is enabled or not and to turn on oroff the switching unit. The integrated circuit may further include acontroller configured to control the circuit block and the switchingunit.

The circuit block may be a block that generates a low frequency noisewhen the circuit block is enabled. The large reservoir capacitor mayhave leakage current and the circuit block consumes power at least 100times greater than power consumed by the leakage current when thecircuit block is enabled.

In accordance with still another exemplary aspect of the presentinvention, there is provided a memory device including a large reservoircapacitor, a switching unit configured to control an electricalconnection between the large reservoir capacitor and at least one powersupply line, and a controller configured to receive external instructioncommands and to turn on or off the switching unit based on an operationmode of the semiconductor device.

The large reservoir capacitor may have leakage current, and theswitching unit may be turned on at an operation mode that consumes powerat least 100 times greater than power consumed by the leakage current.The switching unit may be turned off at one of a power-down mode, astand-by mode, and a refresh mode.

The power supply line may include a first power supply line and a secondpower supply line, and the switching unit may be disposed between thelarge reservoir capacitor and at least one of the first power supplyline and the second power supply line.

The large reservoir capacitor may include a first capacitor group havinga plurality of capacitors coupled in parallel, and a second capacitorgroup having a plurality of capacitors coupled in parallel. The firstcapacitor group may be coupled to the second capacitor group in series.The first capacitor group may be coupled to the second capacitor groupin series.

The capacitor may be a stack capacitor formed by sequentially stacking alower electrode conductive layer, a dielectric layer, and an upperelectrode conductive layer. The large reservoir capacitor has a pF levelcapacitance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a power distributor in accordance withan embodiment of the present invention.

FIGS. 2A and 2B are circuit diagrams illustrating large reservoircapacitors in accordance with another embodiment of the presentinvention.

FIG. 3 is a diagram illustrating an integrated circuit having a powerdistributor in accordance with an embodiment of the present invention.

FIG. 4 is a diagram illustrating an integrated circuit having a powerdistributor in accordance with another embodiment of the presentinvention.

FIG. 5 is a circuit diagram illustrating a memory device having a powerdistributor in accordance with an embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Other objects and advantages of the present invention can be understoodby the following description, and become apparent with reference to theembodiments of the present invention.

FIG. 1 is a diagram illustrating a power distributor in accordance withan embodiment of the present invention.

Referring to FIG. 1, the power distributor in accordance with anembodiment of the preset invention includes a large reservoir capacitor160, a first switching unit 140A, a second switching unit 140B and acontroller 180.

The power supply line includes a first power supply line 120A having apower supply voltage VDD and a second power supply line 120B having aground voltage VSS.

The first switching unit 140A is coupled between the first power supplyline 120A and the large reservoir capacitor 160. The second switchingunit 140B is coupled between the second power supply line 120B and thelarge reservoir capacitor 160. A typical MOS transistor switch is usedas the first and second switching units 140A and 140B. Although thepower distributor in accordance with an embodiment of the presentinvention includes the first and second switching units 140A and 140B,the present invention is not limited thereto. For example, the powerdistributor in accordance with an embodiment may include only one of thefirst and second switching units.

The large reservoir capacitor 160 includes a first capacitor group 160Aand a second capacitor group 160B. The first capacitor group 160Aincludes a plurality of capacitors coupled in parallel, and the secondcapacitor group 160B includes a plurality of capacitors coupled inparallel. The first capacitor group 160A is coupled to the secondcapacitor group 160B in series.

A unit capacitor of the reservoir capacitor 160 may be a stack capacitorformed by sequentially stacking a lower electrode conductive layer, adielectric layer, and an upper electrode conductive layer. Thedielectric is thin to have large capacity such as a μF level capacity.

The controller 180 turns on or off the first and second switching units140A and 140B according to whether a predetermined circuit block (notshown) coupled to the power supply lines 120A and 120B is in operationor not.

The controller 180 determines logical values of control signals CONT and/CONT based on an operation state of a circuit block (not shown) towhich a power supply voltage is supplied through the power supply lines120A and 120B. For example, if a circuit block generates a low frequencynoise when it is enabled or if a circuit block consumes power at least100 times greater than that consumed by a leakage current of the largereservoir capacitor, the controller 180 turns on the first and secondswitching units 140A and 140B when the circuit block is enabled. If not,the controller 180 turns off the first and second switching units 140Aand 140B.

It is possible to obtain small enough impedance using a reservoircapacitor having a small equivalent series resistance (ESR) for radiofrequency noise. However, a reservoir capacitor having very largecapacitance is required for the low frequency noise. Meanwhile, in orderto embody a reservoir capacitor to have a large capacity within alimited area, a stack capacitor having a thin dielectric must be used.However, such a large reservoir capacitor 160 having a thin dielectricmay have large leakage current.

If a circuit block supplied with power from the power supply lines 120Aand 120B is a block generating low frequency noise, a low frequencynoise can be removed by electrically connecting the large reservoircapacitor 160 to the power supply line when the circuit block isenabled. On the contrary, when the circuit block is disabled, the largereservoir capacitor 160 may be disconnected from the power supply lineto reduce leakage current.

If a circuit block consumes power at least 100 times greater thanleakage current of the reservoir capacitor when the circuit block isenabled, the reservoir capacitor 160 may be electrically connected tothe power supply line because the leakage current of the reservoircapacitor is a minimal value that can be ignored. However, when thecircuit block is disabled, the leakage current of the reservoircapacitor is significant in power consumption of an overall system.Therefore, the reservoir capacitor is electrically disconnected from thepower supply lines. For example, if a circuit block is disabled forrelatively long time, the leakage current that steadily flows throughthe reservoir capacitor becomes significant.

The power distributor according to the present embodiment can preventthe leakage current of the reservoir capacitor by controlling anelectric connection between the power supply lines 120A and 120B and thereservoir capacitor 160 based on the operation state.

FIGS. 2A and 2B illustrate a reservoir capacitor in accordance withanother embodiment of the present invention. As shown in FIG. 2A, thereservoir capacitor 260A includes two capacitors 260AA and 260AB coupledin series. As shown in FIG. 2B, the reservoir capacitor 260B may be asingle large capacitor.

FIG. 3 illustrates an integrated circuit having a power distributor inaccordance with another embodiment of the present invention.

Referring to FIG. 3, the integrated circuit in accordance with anembodiment of the present invention includes a circuit block 310, asensor 350, a switching unit 340 and a large reservoir capacitor 360.

The circuit block 310 receives a power supply voltage from first andsecond power supply lines 320A and 320B. The first power supply line320A includes a power supply voltage VDD and the second power supplyline 320B includes a ground voltage VSS.

The sensor 350 detects an operation state of the circuit block 310, andoutputs a control signal CONT as the detection result. That is, alogical value of a control signal CONT outputted from the sensor 350 isdetermined based on an enable state or a disable state of the circuitblock 310.

The switching unit 340 controls an electrical connection between thereservoir capacitor 360 and the first power supply line 320A in responseto the logical value of the control signal CONT.

The switching unit 340 is configured with a PMOS transistor coupledbetween the first power supply line 320A and the reservoir capacitor360. However, the present invention is not limited thereto. Theswitching unit 340 may be configured with an NMOS transistor coupledbetween the second power supply line 320B and the large reservoircapacitor 360. Or, the switching unit 340 may include both of a PMOStransistor and an NMOS transistor.

Unlike the integrated circuit of FIG. 3, the integrated circuit shown inFIG. 4 includes a circuit block 410, a switching unit 440 and acontroller 480.

The circuit block 410 receives a power supply voltage from first andsecond power supply lines 420A and 420B. The first power supply line420A includes a power supply voltage VDD and the second power supplyline 420B includes a ground voltage VSS.

The switching unit 440 controls an electrical connection between thereservoir capacitor 460 and the first power supply line 420A in responseto a control signal CONT.

The controller 480 controls the switching block 440 and the circuitblock 410. In general, a time of operating a predetermined circuit block410 may be controlled by a predetermined control circuit. That is, inthe integrated circuit of FIG. 4, the switching unit 440 is turned on inresponse to the activated control signal CONT outputted from thecontroller 480 only when the circuit block is enabled in response to anenable signal EN outputted from the controller 480.

Referring to FIGS. 3 and 4, the circuit blocks 310 and 410 are each ablock generating a low frequency noise or a block consuming power from apower supply voltage 100 times greater than power consumed by a leakagecurrent of the reservoir capacitor 460 when the circuit blocks 310 and410 are enabled. In this case, the switching units 340 and 440 areenabled when the circuit blocks 310 and 410 are enabled. On thecontrary, the switching units 340 and 440 are disabled when the circuitblocks 310 and 410 are disabled.

In the embodiments shown in FIGS. 3 and 4, the large capacity reservoircapacitors 360 and 460 substantially have the same structure of thelarge capacity reservoir capacitors 160, 260A, and 260B which are shownin FIGS. 1, 2A, and 2B.

FIG. 5 is a circuit diagram illustrating a semiconductor device having apower distributor in accordance with another embodiment of the presentinvention.

Referring to FIG. 5, the semiconductor device in accordance with anotherembodiment of the present invention includes a large reservoir capacitor560, a switching unit 540 and a controller 580. The switching unit 540switches an electric connection between the large reservoir capacitor560 and first and second power supply lines 520A and 520B. Thecontroller 580 receives external instruction commands CS, CAS, RAS, andWE and turns on or off the switching unit based on a memory operationmode.

For example, a memory device including a DRAM has a plurality ofoperation modes. Among the operation modes, the reservoir capacitor maybe coupled to the power supply line in an operation mode that mayconsumes power at least 100 times greater than power consumed by leakagecurrent of the reservoir capacitor. On the contrary, the reservoircapacitor may be disconnected from the power supply line in operationmodes consuming less power. The memory operation modes that consume lesspower are, for example, a power-down mode, a stand-by mode, and arefresh mode.

The memory operation mode is determined by the combination of theexternal instruction commands inputted to a memory chip. Therefore, alogical value of a control signal CONT is determined by the combinationof instructions, and the switching unit 540 receives the control signaland is controlled by the determined logical value of the control signalCONT, thereby determining whether the large capacity capacitor 560 isused or not.

Since the power supply lines 520A and 520B, the switching unit 540, andthe reservoir capacitor 560 of the memory device in accordance withanother embodiment of the present invention have the same structure ofthose in the above described embodiments, detail description thereof isomitted.

As described above, a large capacity reservoir capacitor having μF levelcapacitance may be used to remove low frequency noise. Such largecapacity reservoir capacitor may be implemented as a stack capacitorformed by sequentially stacking a lower electrode conductive layer, adielectric, and an upper electrode conductive layer. The dielectric mustbe thin in order to increase capacitance within a limited area.Therefore, the large capacity capacitor may have large leakage current.

Therefore, in the power distributor and the integrated circuit havingthe same in accordance with the present invention, the leakage currentof the large capacity reservoir capacitor may be blocked by controllingthe electric connection between the power supply line and the largecapacity reservoir capacitor.

That is, if a circuit block receiving a power supply voltage from thepower supply line is a block having a low frequency noise, the largecapacity reservoir capacitor may be electrically connected to the powersupply line when the circuit block is enabled. On the contrary, when thecircuit block is disabled, the large capacity reservoir capacitor may bedisconnected from the power supply line. Also, if the circuit blockconsumes power at least 100 times greater than power consumed by leakagecurrent of the reservoir capacitor when the circuit block is enabled,the reservoir capacitor may be electrically connected to the powersupply line because the leakage current of the reservoir capacitor maybecome small enough to be ignored when the circuit block is enabled. Onthe contrary, when the circuit block is disabled, the reservoircapacitor may be disconnected from the power supply line because theleakage current of the reservoir capacitor may become significant.

A semiconductor device including DRAM has a plurality of operationmodes. The semiconductor device having the power distributor inaccordance with an embodiment of the present invention may connect thereservoir capacitor to the power supply line in an operation mode thatconsumes power 100 times greater than that of any other operation modes.On the contrary, if an operation mode requires less power consumption,the reservoir capacitor may be disconnected from the power supply line.Therefore, it is possible to prevent the leakage current by applying thepower distributor using the reservoir capacitor according to the presentinvention to the memory.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

What is claimed is:
 1. A power distributor, comprising: a capacitor; acircuit block configured to be driven with a power supply voltageprovided from at least one power supply line; a switching unitconfigured to receive information about whether the circuit block isenabled or disabled and to control an electrical connection between thecapacitor and the power supply line in response to the receivedinformation; and a controller configured to control the circuit blockand the switching unit by determining logical values of a control signalbased on an operation state of the circuit block.
 2. The powerdistributor of claim 1, wherein the controller includes a sensorconfigured to determine whether the circuit block is enabled or not andto turn on or off the switching unit.
 3. The power distributor of claim1, wherein the switching unit is configured to be turned on for couplingthe capacitor with the power supply line when the enabled circuit blockgenerates low frequency noise.
 4. The power distributor of claim 1,wherein the switching unit is configured to be turned off so as todecouple the capacitor from the power supply line when the capacitor hasleakage current and the enabled circuit block consumes power at least100 times greater than power consumed by the leakage current.
 5. Thepower distributor of claim 1, wherein the switching unit is configuredto be turned on when the circuit block is enabled, and the switchingunit is configured to be turned off when the circuit block is disabled.6. The power distributor of claim 1, wherein the at least one powersupply line includes a first power supply line and a second power supplyline, and the switching unit is coupled between the capacitor and atleast one the first power supply line and the second power supply line.7. The power distributor of claim 6, wherein the capacitor includes twocapacitors connected in series.
 8. The power distributor of claim 7,wherein the capacitor is a stack capacitor formed by sequentiallystacking a lower electrode conductive layer, a dielectric layer, and anupper electrode conductive layer.
 9. The power distributor of claim 6,wherein the capacitor includes: a first capacitor group having aplurality of capacitors connected in parallel; and a second capacitorgroup having a plurality of capacitors connected in parallel, whereinthe first capacitor group is coupled to the second capacitor group inseries.
 10. The power distributor of claim 1, wherein the capacitor hasa μF level capacitance.
 11. The power distributor of claim 1, whereinthe switching unit is turned on in response to an activation of thecontrol signal outputted from the controller only when the circuit blockis enabled in response to an enable signal EN outputted from thecontroller.